46 lines
1.5 KiB
C++
46 lines
1.5 KiB
C++
#ifndef XGBOOST_REGRANK_UTILS_H
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#define XGBOOST_REGRANK_UTILS_H
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/*!
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* \file xgboost_regrank_utils.h
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* \brief useful helper functions
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* \author Tianqi Chen, Kailong Chen
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*/
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namespace xgboost{
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namespace regrank{
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// simple helper function to do softmax
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inline static void Softmax( std::vector<float>& rec ){
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float wmax = rec[0];
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for( size_t i = 1; i < rec.size(); ++ i ){
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wmax = std::max( rec[i], wmax );
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}
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double wsum = 0.0f;
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for( size_t i = 0; i < rec.size(); ++ i ){
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rec[i] = expf(rec[i]-wmax);
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wsum += rec[i];
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}
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for( size_t i = 0; i < rec.size(); ++ i ){
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rec[i] /= static_cast<float>(wsum);
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}
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}
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// simple helper function to do softmax
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inline static int FindMaxIndex( std::vector<float>& rec ){
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size_t mxid = 0;
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for( size_t i = 1; i < rec.size(); ++ i ){
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if( rec[i] > rec[mxid]+1e-6f ){
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mxid = i;
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}
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}
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return (int)mxid;
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}
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inline static bool CmpFirst(const std::pair<float, unsigned> &a, const std::pair<float, unsigned> &b){
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return a.first > b.first;
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}
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inline static bool CmpSecond(const std::pair<float, unsigned> &a, const std::pair<float, unsigned> &b){
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return a.second > b.second;
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}
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};
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};
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#endif
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